Improved ammonia oxidation by ozone in the presence of bromide ion during water treatment

Ammonia oxidation by ozone proceeds more rapidly in the presence of bromide ion than in its absence. Unlike the direct ozonation of ammonia, the bromide-catalyzed process is little affected by changes in pH. A reaction scheme is proposed in which bromide is oxidized to HOBr, which then brominates ammonia to produce NH₂Br. NH₂Br in turn reacts with O₃ to form NO₃⁻ and also to generate Br⁻, which thus acts as a catalyst. In accordance with the reaction model, zero-order kinetics for ammonia consumption are observed. This work points out once again the importance of Br⁻ as a water quality parameter due to its role as a catalyst in both ozonation and chlorination processes in general.